f a corresponding shape; 2nd, if the tube close at the upper part of
the testicle, 6 c, thus isolating the tunica vaginalis, 6 d, while the
upper part, 6 b, remains pervious, and the internal ring, 6 a, open, and
communicating with the peritonaeal sac, a hydrocele of the cord will
happen distinct from the tunica vaginalis; or this latter may be, at the
same time, distended with fluid, if the disposition of the subject be
favourable to the formation of dropsy; 3rd, the serous tube may close at
the internal ring, form sacculi along the cord, and close again at the
top of the testicle, thus separating the tunica vaginalis from the
abdomen, and thereby several isolated hydroceles may be formed. If in
this condition of the parts we puncture one of the sacs for the
evacuation of its contents, the others, owing to their separation, will
remain distended.

[Illustration: Abdomen and scrotum, showing bone, blood vessels
and other internal organs.]
Plate 40--Figure 2.

PLATE 40, Fig. 3.--Hydrocele of the isolated tunica vaginalis.--When the
serous spermatic tube, 6 b, 6 c, becomes obliterated, according to the
normal rule, after the descent of the testicle, 7, the tunica vaginalis,
6 d, is then a distinct serous sac. If a hydrocele form in this sac, it
may be distinguished from the congenital variety by its remaining
undiminished in bulk when the subject assumes the horizontal position,
or when pressure is made on the tumour, for its contents cannot now be
forced into the abdomen. The testicle, 7, holds the same position in
this as it does in the congenital hydrocele. [Footnote] The radical cure
may be performed here without endangering the peritonaeal sac.
Congenital hydrocele is of a cylindrical shape; and this is mentioned as
distinguishing it from isolated hydrocele of the tunica vaginalis, which
is pyriform; but this mark will fail when the cord is at the same time
distended, as it may be, in the latter form of the complaint.

[Footnote: When a hydrocele is interposed between the eye and a strong
light, the testis appears as an opaque body at the back of the tunica
vaginalis. But this position of the organ is, from several causes,
liable to vary. The testis may have become morbidly adherent to the
front wall of the serous sac, in which case the hydrocele will distend
the sac laterally. Or the testis may be so transposed in the scrotum,
that, whilst the gland occupies its front part, the distended tunica
vaginalis is t